The present invention concerns compounds with at least one (meth)acryl residue, at least one sulfonate or sulfate group as well as a further, usually reactive group, their polymerization products as well as the use of the monomers and the polymers in the medical field, in particular in dentistry. Inasmuch as the invention concerns silane compounds, it also encompasses the condensates available from them as well as their use.
Polymerizable organic compounds with acid groups are important components for medical products for achieving desired material properties like wetting, etching effect, complexing, and thereby adhesion on biological interfaces. Dental adhesives are based on such conventional monomeric compounds, but exhibit still some considerable deficits. An essential problem in this context is that the etching effect is often insufficient within the context of self-etch application for realizing the necessary retentive structures required for the adhesion and thus a long-lasting connection between dental tissue and restoration material. Therefore, a prior separate etching step with an etching gel cannot be avoided; this, in turn, increases the susceptibility for errors and the treatment costs. Concerning the increasing demands in regard to biocompatibility (reference is being had to the allergy discussion in connection with dental monomers), the above systems also offer no solution. Since the components of the adhesive in case of a restoration come closest to the tooth roots as well as blood vessels, it is of special interest from a toxicological viewpoint to provide systems that are free of monomers.
In the patent application DE 44 16 857 C1, carboxylic acid-functionalized (meth)acrylate alkoxysilanes are described. They are characterized by a plurality of possibilities for varying or adjusting the properties of the inorganic-organic composite polymers produced therefrom. As a result of the contained carboxylic acid groups, additional reaction possibilities (e.g., glass ionomer reactions) as well as an improved adhesion on inorganic surfaces arise. The etching effect (see self-etch application) of a carboxylic acid group is however nowhere as strong as it is sometimes desired. The same holds true for the phosphonic acid-based systems disclosed in EP 1 377 628 B1. Therefore, up to now, it is not possible to obtain with hybrid polymer-based systems a stable enough connection between dental tissue and restoration material in the context of the desirable self-etch application.
For several application purposes, like the stabilization of aqueous silicates or the production of electro-viscous liquids, emulsifiers, detergents or foaming agents, monomeric or condensed silanes containing sulfonate or sulfate groups have been developed. Thus, U.S. Pat. No. 6,777,521 discloses silicone sulfate polymers which are obtainable by the reaction of suitable epoxy compounds with metal sulfate. U.S. Pat. No. 3,328,449 discloses sulfopropylated organo-functional silanes and siloxanes which can be obtained by means of reacting sultones. Organo siloxane sulfosuccinates in which a sulfonated succinic acid ester is bonded by the oxygen atom of the ester group by an alkylene group to a silicon atom are disclosed in U.S. Pat. No. 4,777,277. The preparation of a hydrolytically condensable bis-sulfosuccinate amide of a diaminosilane, obtained by the reaction of the free carboxylic acid of the corresponding succinate amide with sodium sulfite, is disclosed in example 1 of U.S. Pat. No. 4,503,242. A silane which carries a sulfonate group and a hydroxyl group at an alkylene oxyalkylene residue of the silicon is disclosed in U.S. Pat. No. 5,427,706.
The use of purely organic monomers which carry a terminal sulfonate group as well as an unsaturated olefinic group for concurrent etching and base-coating (“priming”) of teeth is suggested in US 2002/0119426 A1. The employed AMPS (2-acrylamido-2-methylpropane sulfonic acid) is a commercially available product. U.S. Pat. No. 6,759,449 B2 also discloses dental adhesive compositions which carry an organically polymerizable (meth)acrylic acid group as well as an acidic group. In this context, no distinction is made between sulfonate groups and phosphonate groups or other acidic groups concerning the usability of the compounds and their properties. The same holds true for US 2003/0055124 A1; only for the (meth)acrylamido phosphonic acids, but not for the also disclosed corresponding sulfonic acids, information is provided for the preparation. Another application, US 2008/0194730, essentially by the same group of inventors, suggests again for dental composites the use of self-etch polymerizable N-substituted (meth)acrylic acid amide monomers which carry additionally an acidic unit, selected from phosphonic acid units and sulfonic acid units. N-methacryloyl aminoalkyl sulfonic acids can be used according to the disclosure of EP 1 421 927 A1 as self-etch primers for dental purposes.
DE 102 06 451 A1 discloses dental adhesive compositions from acidically polymerizable nanoparts in an aqueous phase. The nanoparticles consist of siloxanes having acidic as well as organically polymerizable groups bonded thereto. The acidic groups can be either phosphonate groups or sulfonate groups; individual specific advantages for one or the other group are not specified. The only example of use discloses a specific adhesion value of a dental adhesive, made from a phosphonic acid-containing material, on a tooth surface. A process for producing sulfonate group-containing silanes is neither mentioned generally nor in regard to the illustrated compounds.
There is a need for organically polymerizable monomers of superior properties for the application in particular in the dental field. Here, an improved adhesion and/or an improved etching function and/or an adaptation of the optical properties for the cosmetic appearance are especially relevant. To provide a remedy in this context is the object of the present invention.